Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: (qmail 83453 invoked from network); 4 Feb 2004 11:26:07 -0000 Received: from unknown (HELO ptb-mxscan01.plus.net) (212.159.14.235) by ptb-mailstore01.plus.net with SMTP; 4 Feb 2004 11:26:07 -0000 Received: (qmail 39239 invoked from network); 4 Feb 2004 11:26:10 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore01.plus.net (212.159.14.215) by ptb-mxscan01.plus.net with SMTP; 4 Feb 2004 11:26:04 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim 4.30; FreeBSD) id 1AoLAR-0009m3-T5 for dave@picks.force9.co.uk; Wed, 04 Feb 2004 11:26:04 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AoL9R-0006w2-Io for rs_out@blacksheep.org; Wed, 04 Feb 2004 11:25:01 +0000 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 1AoL9Q-0006vt-Gt for rsgb_lf_group@blacksheep.org; Wed, 04 Feb 2004 11:25:00 +0000 X-Fake-Domain: gemini Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 1AoKSw-0000Tw-00 for rsgb_lf_group@blacksheep.org; Wed, 04 Feb 2004 10:41:06 +0000 X-No-DNS-For: 147.197.232.252 Received: from [147.197.232.252] (helo=rsch15) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 1AoKSv-0006lK-00 for rsgb_lf_group@blacksheep.org; Wed, 04 Feb 2004 10:41:05 +0000 From: "James Moritz" <J.R.Moritz@herts.ac.uk> To: rsgb_lf_group@blacksheep.org Date: Wed, 4 Feb 2004 10:41:03 -0000 Organization: University of Hertfordshire X-Bad-Message-ID: no DNS (rsch15) Message-ID: <000001c3eb0b$63eb52c0$fce8c593@rsch15> MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2627 Importance: Normal In-reply-to: <1075840476.402005dcb4653@webmail2.kuleuven.be> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-UH-MailScanner: No Virus detected Subject: RE: LF: RE: Re: Re: G0MRF 300w Tx & DDS VFO Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: <owner-rsgb_lf_group@blacksheep.org> Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 2 Dear Rik, Gary, LF Group, >If that is the case there is no need to get a nice sine (through a LPF >and bufferamplifier), most convenient is to pick up the 274kHz signal >somewhere at TLL or CMOS level. >73, Rik ON7YD The output of the DDS is actually the output of a digital to analogue converter, and at 274 kHz the signal on the output pin of the DDS chip will be a pretty good approximation to a sine wave anyway. The function of filtering in the circuit is to remove "alias" frequency components arising due to the sampled-data nature of the output signal. So there isn't actually a logic-level signal in the circuit. You could of course add a squaring circuit giving a logic-level square wave after the DDS output filter. Cheers, Jim Moritz 73 de M0BMU